JP5381411B2 - Stereoscopic display image and diffraction grating recording medium - Google Patents

Description

The present invention relates to a three-dimensional display image, in particular, a three-dimensional diffraction grating configured using hologram technology, and a medium (diffraction grating recording medium) provided with the diffraction grating,
The diffraction grating is observed in a three-dimensional space with a binocular parallax arranged in a certain direction and floating, and the observer simply changes the observation angle a little to change the diffraction grating over the diffraction grating. The present invention relates to a stereoscopic display image having excellent anti-counterfeiting properties and a medium (diffraction grating recording medium) on which the image moves at a speed determined in the arrangement direction.
Since the diffraction grating and the medium to which the diffraction grating is attached are determined to be genuine by the “light movement in the three-dimensional space” of the diffraction grating, it is easy for the determiner to determine the movement. It is necessary that the diffraction grating regions are arranged in a certain direction with a size and an interval.
Of course, the “certain direction” is not limited to a linear direction, but may be a polygonal line shape, a curved line shape, a plurality of directions at the same time, or a reverse direction at the same time.
The more complicated this direction is, the more reliable the authenticity judgment is and the higher the security.
Furthermore, the speed of the “light movement” can also be changed, and the determination of the authenticity can be made easily and by conveying these “light movements in the three-dimensional space” to the authenticity judge who is an observer in advance. It can be certain.
The present invention includes gift certificates such as gift certificates, securities, stock certificates, various cards such as credit cards, prepaid cards, ID cards, tickets, banknotes, passports, identification cards, various certificates, appraisals, certificates, public competitions Used for various anti-counterfeiting media such as voting tickets, video software, personal computer software (hereinafter referred to as security objects), such as authenticity determination sheets, seals, transfer foils, and threads.
In general, the visible region is “purple”: 380 nm to 450 nm, “blue”: 450 nm to 495 nm, “green”: 495 nm to 570 nm, “yellow”: 570 nm to 590 nm, “orange”: 590 nm to 620 nm, “red”: 620 nm Although it is divided into ˜750 nm, the change is continuous, and this classification is an example.
A diffraction grating constructed using a hologram technique such as an optical method or an electron beam drawing method can be observed by observing the diffraction grating with sunlight or a white light source such as a white fluorescent lamp. The wavelength components are separated according to the “grating angle” and “diffraction grating period (pitch)”, and then diffracted to a predetermined angle, so the observer observes light of various colors according to the observed angle. can do.
Usually, the first-order diffracted light of the diffraction grating is observed, and a predetermined diffraction grating pattern provided on the medium (meaning a shape such as a colored pattern formed in the diffraction grating region) is displayed at an angle. After recognizing as a “red pattern”, the observation angle is shifted by about 10 degrees, whereby the change in the color of the light can be confirmed as “yellow”, “green”, “blue”.
The speed at which light on this diffraction grating (means diffracted light) or the color tone of light moves (the place where the light is diffracted with the same color tone moves) depends on the speed at which the angle of observation is changed. Then, when the diffraction grating is continuously changed (the diffraction grating angle and the diffraction grating period are continuously changed according to the position of the illumination light source and the observation angle), the region of light of the same color tone is formed. If the diffraction grating forming surface is observed to move at a predetermined speed and is changed continuously finely, the change becomes smooth.

In the present invention, the diffraction grating is formed so as to generate a stereoscopic view due to binocular parallax, the diffraction grating is separated from the diffraction grating forming surface, and is floated in the three-dimensional space, and the solid floating in the space is formed. The diffraction grating is continuously formed in a certain direction on a typical diffraction grating (by forming intermittently in the space at a predetermined interval, a constant speed is achieved on the diffraction grating surface of a group of diffraction gratings connected in a certain direction. When the observation angle is shifted little by little, the light on the diffraction grating moves on the orbit in the three-dimensional space according to the change in the observation angle. In addition, the movement can be expressed in conjunction with a change in color tone from “red” to “blue”.
This confirmation, that is, “determination” is sufficiently possible even under a white light source, but can be performed more accurately and reliably by using a monochromatic light source such as an LED.
In order to analyze this motion and create the same one, it is necessary to digitize the motion in the three-dimensional space and to perform complicated processing similar to the computer-generated hologram technology. Although it is difficult, its three-dimensional movement is defined as “authentication proof pattern” in advance, and its reproducibility is high, so its authenticity can be easily determined visually. It is possible to provide an anti-counterfeit medium having high convenience and high anti-counterfeit property.

(Main applications)
The main application of the stereoscopic display image composed of fine lines according to the present invention is to prevent damages to the counterfeit prevention field, specifically, credit cards, etc. Obtained, driver's license, identification card such as employee ID card, membership card, various certificates, appraisals, certificates, entrance examinations, passports, banknotes, gift certificates, point cards, stock certificates, securities There are lottery tickets, horse tickets, bankbooks, boarding tickets, pass tickets, air tickets, admission tickets for various events, play tickets, prepaid cards for transportation and various telephones.
All of these are information records that hold information of economic or social value, identity identification, etc., and can identify the authenticity of the record itself for the purpose of preventing damage caused by forgery. Although it is desired to have a function, the present invention is applied to a method in which the confirmation method is visual and it is particularly desired to have a function to prove the authenticity of the visual determination.
In addition to the uses described above, expensive products such as luxury watches, luxury leather products, precious metal products, jewelry, etc., often referred to as luxury brand products, or storage boxes for these expensive products And cases can also be forged. In addition, mass-produced products of famous brands, such as audio products, electrical appliances, etc., or tags that are hung on them are also subject to forgery.
Furthermore, a storage body in which music software, video software, computer software, game software, or the like, which is a copyrighted work, or cases thereof can also be forged. In addition, it is desirable that products such as printer toner, paper, and the like in which supplies to be replaced are limited to genuine materials have a function of identifying their authenticity for the purpose of preventing damage caused by forgery.
A forgery prevention body or the like that can be visually judged is added to these security objects in a form such as sticking, and the authenticity of the security object is proved by the visual judgment.
In the present specification, “ratio”, “part”, “%” and the like indicating the composition are based on mass unless otherwise specified.

(Background technology)
2. Description of the Related Art Conventionally, printed banknotes such as securities and banknotes have been used for printing to prevent counterfeiting. A conventional chromatic pattern consists of a geometric pattern made by complexly combining thin lines such as wavy lines. However, due to the higher resolution and improved color reproducibility of color copiers, forgery of such vouchers has increased.
In addition, in order to improve anti-counterfeiting, a color pattern using a diffraction grating has been put into practical use. The chromatic pattern by the diffraction grating can express the movement of light and can express a fine pattern with high resolution although it is a two-dimensional image, and is often used as an advanced anti-counterfeiting means.
However, even the diffraction pattern on the diffraction grating, which has been thought to be an advanced anti-counterfeiting technology, can now be found by recording with a microscope or by observing the movement of light. Counterfeiting has increased due to the widespread use of diffraction grating image creation devices by interference.
By the way, conventionally, a computer-generated hologram (CGH) capable of reproducing a stereoscopic image is known. There are roughly two methods for creating such a CGH, one of which is a method of replacing the object surface known in Non-Patent Documents 1, 2, etc. with a set of point light sources. The other is a holographic stereogram method known from Patent Document 1, Non-Patent Document 3, and the like.

Here, as a representative example, a method of replacing the former object surface with a set of point light sources will be described. As an example of CGH, an outline of a binary hologram in which the intensity distribution of interference fringes is recorded and a reproduced image has only a horizontal parallax and is observed with white light from above will be described. As shown in FIG. 4, in step ST1, it is defined by the shape of the object to be converted to CGH. Next, in step ST2, the spatial arrangement of the object, the CGH surface, and the reference light is defined. Next, in step ST3, the object is vertically divided by slicing on the horizontal plane, and further replaced with a set of point light sources on the slice plane. Then, in step ST4, based on these spatial arrangements, the intensity of interference fringes between the light reaching from each point light source constituting the object and the reference light is obtained by calculation at each sample point defined on the CGH plane. Interference fringe data is obtained. Next, in step ST5, the obtained interference fringe data is quantized, and then converted into EB drawing rectangular data in step ST6. In step ST7, the data is recorded on the medium by the EB drawing apparatus to obtain CGH. .
When calculating the interference fringes, hidden surface removal processing or the like is performed. This hidden surface erasure process is a process of making the portion hidden behind the front object invisible when observing the object from a certain viewpoint, and this process adds information on the overlap of the object to the retinal image, This is a process capable of obtaining a three-dimensional effect.
In addition, in GGH by the method of replacing such an object surface with a set of point light sources, a technique for reproducing color when reproduced with white light is proposed in Patent Document 2.
Furthermore, such a three-dimensional pattern can be formed as a transfer foil or label, and can be used as a document such as a security or banknote transferred or pasted.

Japanese Patent No. 3,155,263 JP 2000-214751 A

“Image Lab” April 1997 (Vol.8, No.4) pp. 34-37 “3D Image Conference '99 -3D Image Conference '99-” Lecture Collection CD-ROM (June 30-July 1, 1999, Kogakuin University Shinjuku Campus), Paper “Image Binary CGH by EB Drawing ( 3)-Improvement of stereoscopic effect by hidden surface removal and shading- "The 3rd Hodic Lecture Lecture Collection" (November 15, 1996, Nihon University Surugadai Campus Building No. 1 Second Conference Room) sponsored by the Holographic Display Society (Japan Optical Society, Japan Society of Applied Physics) Acceleration of 2D image sequence generation for holographic stereograms "

The chromatic pattern by the diffraction grating and the like described above is fixed on the formation surface, and although it can partially express the movement of light, the movement of the light is on the fixed chromatic pattern design. The shining area part of the shape of the illumination light source (for example, a linear area in the case of a linear fluorescent lamp) only moves like the movement of a “rainbow”, and the recorded color pattern is three-dimensional. There is no sense and there is no relation between the movement of light and authenticity determination.
As described above, for example, the anti-counterfeiting diffraction grating has a chromatic pattern fixed on the medium (paper surface) as in the conventional intaglio printing on the paper surface. Although it is difficult to copy with a color copier, it has only the hurdle of “difficult to produce the same”, and how it looks when visually observed There was no significant change, and the security was slightly inferior from the viewpoint that the authenticity can be easily and reliably determined by visual determination.

  Accordingly, the present invention has been made to solve such problems. The purpose is to produce a new effect that does not exist in conventional diffraction gratings for visual judgment, and the light moves on the diffraction grating with a slight shift of the observation angle. is there. Then, by utilizing the pseudo stereoscopic effect due to binocular parallax, the processing burden can be reduced as compared with the computer-generated hologram processing of the three-dimensional object itself, and the stereoscopic image itself becomes brighter and clearer. It is possible to express "motion" having high reproducibility in the speed and position defined in the three-dimensional space as "motion of light", and it is possible to easily determine the authenticity with high reliability. A stereoscopic display image and a medium to which the stereoscopic display image is attached are provided.

To solve the above problem,
The first aspect of the present invention is:
Plural pieces of (n: n ≧ 2) the diffraction grating region is arranged in a predetermined direction with a shape represented by a diffraction grating having a diffraction grating angle and grating period are formed, and each of the diffraction grating region adjacent to, it becomes the diffraction grating region paired, n the diffraction grating region adjacent diffraction grating region having the same shape and at least one provided in which three-dimensional display image (diffraction grating region and adjacent diffraction grating region as one set Consisting of a pair)
Each diffraction grating region and the adjacent diffraction grating region to be paired are arranged so that a part of the region overlaps with the region,
The diffraction grating angle θn and the diffraction grating period dn of each diffraction grating region change in the predetermined direction at a predetermined ratio of the diffraction grating angle θ0 and the diffraction grating period d0, and
A diffraction grating angle of a diffraction grating in an adjacent diffraction grating region paired with each diffraction grating region is different from the diffraction grating angle θn of the diffraction grating region by α (diffraction grating angle = θn + α) .

The second aspect of the present invention is:
A plurality of (n: n ≧ 2) the diffraction grating region is arranged in a predetermined direction with a shape represented by a diffraction grating having a diffraction grating angle and grating period are formed, and each of the diffraction grating region adjacent to, it becomes the diffraction grating region paired, n the diffraction grating region adjacent diffraction grating region having the same shape and at least one provided in which three-dimensional display image (diffraction grating region and adjacent diffraction grating region as one set Consisting of a pair)
Each diffraction grating region and the adjacent diffraction grating region to be paired are arranged so that a part of the region overlaps with the region,
The diffraction grating angle θn and the diffraction grating period dn of each diffraction grating region change in the predetermined direction at a predetermined ratio of the diffraction grating angle θ0 and the diffraction grating period d0, and
A diffraction grating period of a diffraction grating in an adjacent diffraction grating area paired with each of the diffraction grating areas is characterized by being different from the diffraction grating period dn of the diffraction grating area by β (diffraction grating period = dn + β) .

The third aspect of the present invention is:
First, a standing body display diffraction grating recording medium on which an image is formed according to any one of the second aspect.

A chromatic pattern is a geometric pattern that combines straight lines, curved lines, wavy lines, arcs, circles, etc., and the complexity of the design, as well as the thickness of fine lines, such as chromatic patterns by intaglio printing. It is a thing that is gradually thinned or divided into multiple lines like brush writing, and has a copy check function and a forgery prevention function that makes it difficult to create the same thing.
As a motif of a hologram or a diffraction grating, a method of expressing a three-dimensional effect by using a flat design on the formation surface of the diffraction grating or the back side or the near side is used. Depending on the use, forgery-preventing characters, symbols, geometrical patterns, stencils, etc. are used from artistic objects representing natural objects.
However, in this case as well, it only has a rainbow color or color expression under a predetermined illumination light source, and also has a copy check function and a forgery prevention function that makes it difficult to create the same thing. . Of course, when observing these, there is a phenomenon in which the color tone or bright line moves due to the movement of the illumination light source, etc. However, there is no such means as a means of proof of authenticity. It does not stipulate any specific movement.
On the other hand, the “shape” in the “diffraction grating region having a shape represented by a diffraction grating having one diffraction grating angle and one diffraction grating period” in the present invention refers to the above-mentioned hologram or diffraction grating motif. This means an individual character, symbol, or figure in, but in this "shape" sequence, "light" moves from "shape" to the next "shape" and emits that light. Since the “shape” is floating in the three-dimensional space, the movement of the “light” moves in the three-dimensional space at a predetermined speed along a predetermined three-dimensional trajectory.

This “shape” is provided on the security object, like a chromatic pattern, a planar diffraction grating used for security applications, or a hologram image forming a three-dimensional stereoscopic image. Since the object is determined (certified) to be authentic, information related to the security object, such as the company name indicating the person who issued the security object, the manufacturer name, the service name of the product, etc. Predetermined items such as a “logo” to be displayed, an identification number, a management number, a common keyword used for genuine products, and characters, symbols, figures, etc. related to other security objects are preferably used.
Furthermore, because it is necessary to accurately determine the situation where “light moves” from the “shape” to the next “shape” one after another at a predetermined speed, ”(Light trajectory) is easy to grasp, has almost the same size, has an area that can be visually judged (width as the trajectory), and can recognize the moving speed (if there is a gap, It is necessary to line up in order to lose sight of the next position.)
If the number of “shapes” is two or more, the determination is valid, but “the direction in which light moves and the speed at which it moves in the three-dimensional space” is used for the “authenticity determination”. A large number is desirable in terms of expressing more complex movements and improving the reliability of determination. Furthermore, only a part of the “shape” group may be “for determination”, and the other part may be positioned as a camouflage.
However, when the observer visually observes, it is necessary to be able to easily identify “movement of light” for determination among various lights. It is necessary to arrange an arrangement representing another “movement of light” at a distance so as not to make an erroneous determination.
In particular, under multiple fluorescent lamps in a general observation environment (for example, merchandise transaction place, office work place, etc.) or under a diffused light source, the number of illumination light sources is the same as this "shape" sequence. “Light” is generated, making it difficult for the observer to judge. Therefore, the observer determines with a white light source only under one fluorescent lamp, with a single incandescent bulb, a hand-held LED, or even a light source of a simple penlight. If the “shape” is uniformly formed on one surface, a plurality of movements of light are recognized, and the “movement of light for determination” cannot be specified.

Therefore, the stereoscopic display image or diffraction grating recording medium of the present invention provided on the security object is assumed to be an authenticity judgment scene, for example, an upper white point light source or a single white fluorescent lamp. In addition, when the security object is tilted 45 degrees and visually observed from a position 30 to 40 cm away from the security object, the security object is gently tilted continuously from -30 degrees to +30 degrees. The "movement of light" moving from the "shape" to the "shape" can be reliably recognized, and the "movement" is communicated to the observer who is the observer in advance as a "judgment pattern" Therefore, it is assumed that the size of the “shape” is 300 μm or more and is represented by a line width of 30 μm or more. The interval of “shape” is smaller than the size of “shape”. Furthermore, it is assumed that “shapes” are arranged only in a certain direction in which “light moves”, and at least an interval larger than the size of “shape” is provided in the other directions.
The “direction” of the “shape” may be a straight line such as “horizontal direction, left to right”, or may be a movement with up-down movements such as a quadratic curve, a cubic curve, and other higher-order curves. There may be. Further, the three “movements of light” may be divided into a linear direction in the middle and up and down in the vertical direction.
Furthermore, it may be one that moves in both directions simultaneously, such that one “light” moves from left to right and another “light” moves from right to left.

The “shape” of the present invention floats in the three-dimensional space from the formation surface of the diffraction grating or the like by stereoscopic viewing using binocular parallax, and the movement of the light described above is the “shape” floating in the air. The robot moves at a predetermined speed while drawing a three-dimensional trajectory in the three-dimensional space.
The speed of the “light movement” is determined by a predetermined ratio θ0 and d0 in which the diffraction grating angle θn and the diffraction grating period dn of the diffraction grating region representing the “shape” change in a certain direction (direction of the movement). Determined.
θ0 is set to ± 3 degrees to ± 20 degrees depending on the size of the interval between the “shapes”. If the magnitude of the change is less than 3 degrees, the movement is slow, so it is difficult to specify. If it exceeds 20 degrees, the movement becomes discrete and it is difficult to grasp the speed. In particular, 5 to 10 degrees is a smooth movement, which is suitable for determination.
d0 is set to ± 0.03 μm to ± 0.3 μm. If the magnitude of the change is less than 0.03 μm, it is difficult to specify because the movement is slow, and if it exceeds 0.3 μm, the movement becomes discrete and it is difficult to grasp the speed. In particular, 0.05 μm to 0.10 μm is suitable for determination because smooth movement is obtained.
In order to express binocular parallax when observing at a distance of 30 cm to 40 cm from the security object to be observed, the diffraction angle θn of the original diffraction grating region is added to the diffraction grating angle in the adjacent diffraction grating region. The diffraction grating angle α is set to ± 5 degrees to ± 45 degrees. In order to obtain more stable binocular parallax with a relatively wide field of view, it is preferable to increase or decrease by 10 to 25 degrees. If it is less than 5 degrees or exceeds 45 degrees, it is difficult to recognize binocular parallax anymore. If the change is 5 degrees or less, the stereoscopic effect is slightly poor. If the change is 45 degrees or more, it is easy to recognize it as another diffraction grating region. Further, even within this range, 15 to 20 degrees is optimal.

However, when the observation distance is smaller than the set value or far, it is desirable to use a smaller or larger angular change.
Similarly, the diffraction grating period β added to the diffraction period dn of the original diffraction grating area is set to ± 0.05 μm to ± 0.40 μm with respect to the diffraction grating period in the adjacent diffraction grating area. When the magnitude of the change is less than 0.05 μm or exceeds 0.4 μm, it is no longer possible to recognize binocular parallax. When the change is less than 0.05 μm, the stereoscopic effect is slightly poor, and when the change exceeds 0.4 μm, it is easy to recognize as another diffraction grating region. Furthermore, even within this range, 0.10 μm to 0.20 μm is optimal.
The distance that rises from the diffraction grating formation surface by stereoscopic viewing (moves away from the back side or approaches the near side) is determined by a predetermined movement D. This D is 40 μm to 400 μm.
Although the predetermined movement D also depends on the observation distance, when there is one adjacent diffraction grating region, binocular parallax appears even when the distance between the regions is within a range of 10 μm to 500 μm. When there are a plurality of fine lines and they are set in a complicated manner, they are all provided so as to fall within this range.
However, a stable stereoscopic effect is obtained at 40 μm to 400 μm under the observation environment described above. Furthermore, depending on the diffraction grating and its shape, 40 μm to 200 μm is more desirable.
This D can take any value depending on the position of the “shape” (upper, middle, lower, etc.), but the set of these values may be a constant value that is the same as the other “shape”. it can. In that case, the “shape” that is tilted in the depth direction in the space or that the “shape” itself is observed to be deformed to the front or back is shining one after another while maintaining the same tilt and deformation state. Observed. In this case, although the individual “shape” looks more complex under a white light source, it may not be expected to be observed to move at a constant speed with a predetermined deformation on the near side and the far side. , Can increase its unexpectedness.

Further, when the predetermined movement D is randomly set in each “shape”, the “movement” that is observed to be inclined in the depth direction in this space or that the “shape” itself is deformed to the front or back is “ Not only does the “shape” change to the front or back, but the “shape” itself shows complex deformation, and it is physically impossible to analyze the “movement” from observation with a light source. Can be impossible level.
Moreover, since the authenticity judge knows the information about the “movement” in advance, it may confirm the moving speed, confirm the partial movement, or check the combination. Since the authenticity can be determined, it is possible to provide a three-dimensional diffraction grating pattern that is highly anti-counterfeiting and easy to visually check, and a medium with the diffraction grating pattern.
At any rate, the distance to be lifted should be within ± 10 mm. If it exceeds ± 10 mm, the brightness of the “shape” decreases, so that the observer may make a determination error. Since the brightness decreases as the distance from the diffraction grating surface increases, it is more preferably within ± 5 mm.
However, in consideration of this decrease in brightness, it is also preferable to adjust the brightness by increasing the diffraction grating line width constituting the “shape” by 10% to 30%.
As described above, when one adjacent diffraction grating region is provided, binocular parallax occurs, and one “shape” of the diffraction grating region can be observed at a position raised from the formation surface in the intermediate region. Form two or more diffraction grating regions in the same way, ie, four, six to eight, or one to the left and right of the original diffraction grating region. The depth of view can be increased and the viewing angle can be enlarged. However, the overlapping portion of the diffraction grating region and the adjacent diffraction grating region is doubled, tripled, or even ninefold, and the brightness is increased. (For the double portion, regions of diffraction gratings of 10 μm to 50 μm square are alternately formed in a checkered pattern by each diffraction grating. The interference effect of the lattice group In the case of 50 μm square or more, the checkered pattern is visually observed as uneven brightness, and is not suitable for authenticity determination. Etc.), the overall brightness decreases, so even if individual diffraction gratings with high diffraction efficiency (20% or more) are used, the adjacent diffraction grating areas are One to three is desirable.

Preferably, one is formed on each of the left and right sides of the original diffraction grating region (in the case of two adjacent diffraction gratings), so that the three-dimensional effect is sufficient while ensuring the brightness, and the overlapping portion. Can be minimized.
The adjacent movement D is desirably moved in the horizontal direction assuming the observation environment, but from the lower right (lower left) to the upper right (lower right) depending on the way of observation and the shape of the “shape”. It is also desirable to move at an angle, such as 10 to 30 degrees.
Also, in the case where the “light movements” themselves are crossed, the multiple recording process is performed so that the brightness of the overlapping portion of the diffraction grating (multiple recording region) does not vary greatly. Brightness can be ensured.
In addition, by changing the arrangement of the individual “shapes” in part, not at regular intervals, the speed of “light movement” can also be changed, and these “light movements in the three-dimensional space” can be changed. By telling the authenticity judgment person who is an observer in advance, the judgment can be made easy and reliable.
As a more advanced anti-counterfeiting method, if the observation angle is changed slowly, it is possible to have an angle at which at least one “shape” in the judgment “shape” line disappears for a moment. In order to prevent the image from being reproduced at an observation angle width of about 5 degrees to 10 degrees, the diffraction grating region has a diffraction grating angle (10 degrees to 20 degrees) or a diffraction grating period (0.2 μm). ˜0.4 μm) can be discontinuous (meaning that one in this range is not used).

Further, the same diffraction grating condition can be set so that there is an angle at which the movement of light stops when the observation angle is changed slowly.
Furthermore, the above-mentioned disappearing angle and stopping angle are synchronized with the design such as printing on the security object, and this phenomenon occurs at a position indicating a specific number or character on the design. Applications such as suggesting further “hidden information” are also possible.
For example, a 3D display medium of the present invention is formed on a printed random number, and the movement of light moves on the number, and the “number corresponding to the above-mentioned disappearance angle or stop angle”. "Can be used as the" hidden information ".
Stereoscopic viewing with binocular parallax is very bright and stable, unlike the case where interference fringes of objects arranged in a three-dimensional space are formed on the recording surface by a computer-generated hologram, and the “motion of light” is authentic. Suitable for use in judgment.
For example, if an alphabetic character string “ABCDEF” having a line width of 1 mm, a character height of 5 mm, and a character width of 4 mm is defined as the “shape” group, and each has one adjacent adjacent diffraction grating region, the specification of each diffraction grating As
(Diffraction grating period dn, diffraction grating angle θn, predetermined movement D, period change d0, angle change θ0, angle change α of adjacent diffraction grating region, d0 = 0.1 μm, θ0 = 6 degrees)
A: d1 = 0.7 μm, θ1 = −24 degrees, D = 80 μm
Adjacent region of A (α = 15 degrees): period = 0.7 μm, angle = θ1 + α = −9 degrees B: d2 = 0.8 μm, θ2 = −18 degrees, D = 120 μm
Adjacent region of B (α = 15 degrees): period = 0.8 μm, angle = θ2 + α = −3 degrees C: d3 = 0.9 μm, θ3 = −12 degrees, D = 160 μm
Adjacent region of C (α = 15 degrees): period = 0.9 μm, angle = θ3 + α = 3 degrees D: d4 = 1.0 μm, θ4 = −6 degrees, D = 160 μm
Adjacent region of D (α = 15 degrees): period = 1.0 μm, angle = θ4 + α = 9 degrees E: d5 = 1.1 μm, θ5 = 0 degree, D = 120 μm
E adjacent region (α = 15 degrees): period = 1.1 μm, angle = θ5 + α = 15 degrees F: d6 = 1.2 μm, θ6 = 6 degrees, D = 80 μm
An adjacent region of F (α = 15 degrees): period = 1.2 μm, angle = θ6 + α = 21 degrees, and the distance between “shapes” is 2 mm and arranged in the horizontal direction to form a stereoscopic display image.

When the stereoscopic display image is observed under the above-described observation conditions, “light moves at a constant speed” from the left to the right, and each “shape” is further away from the position of the three-dimensional space away from the formation surface, It is possible to confirm the “movement of the light in the perspective direction” approaching again, that is, “the movement of the three-dimensional light”.
The diffraction grating area and the corresponding part of the adjacent diffraction grating area need to have the same width with high accuracy. If this width is different, the sense of distance from the diffraction grating formation surface becomes unstable in stereoscopic viewing by binocular parallax.
Therefore, in order to be able to observe line width, sense of distance, and movement with high accuracy, high pattern shape accuracy by electron beam drawing and unevenness uniformity by high-precision photoresist process with constant diffraction efficiency Furthermore, a highly accurate physical unevenness duplicating step and a reflecting film forming step having uniform reflectivity are required. If the diffraction efficiency differs by several percent, the determination accuracy is affected.
In order to perform visual determination, the reference light source is assumed to be in the visible region (for example, 380 nm to 750 nm), and the movement of light in the stereoscopic display image under the illumination is observed.
By including the movement of light in the perspective direction, it is physically impossible to reproduce the same movement only from the observation means, and in this sense, anti-counterfeiting is high.
In addition, the movement can be determined in detail at the design stage, and after completion, the detailed movement can be easily confirmed in the authenticity determination.
In the above example, an alphabetic character having a line width of 1 mm is assumed, the specification of the diffraction grating on the line is defined, and the diffraction grating specification change in the adjacent diffraction grating region is defined as the diffraction grating angle α (= 15 degrees). The change in the grating specification can be made a diffraction grating period β (for example, β = 0.2 μm).
These selections are made in consideration of the high and constant diffraction efficiency.

In the first to tenth aspects of the present invention, the diffraction grating inputs data related to the diffraction grating calculated by a spatial arrangement or the like set for a predetermined “shape” to the electron beam drawing data editing PC, The electron beam drawing data of the line drawing apparatus is edited, recorded on the electron beam drawing resist using the electron beam apparatus, and subjected to development processing to obtain a diffraction grating master. This diffraction grating master is overlaid on a relief forming sheet in which a base material and a transparent resin are laminated, and is replicated by predetermined heating and pressurizing, and a predetermined diffraction grating relief (three-dimensional diffraction grating) is formed on the transparent resin. After the pattern is formed, a reflective thin film is formed and an adhesive is applied to form a diffraction grating label (medium with a diffraction grating pattern), that is, a diffraction grating recording medium. Of course, it can be transferred and formed as a transfer foil, or can be wound into a paper medium or the like as a thread.
This diffraction grating recording medium can be affixed to various security objects, and can be used for authenticity determination of security objects.

  According to the present invention, there is a new effect that does not exist in conventional diffraction gratings for visual determination, and the `` shape '' expressed in the diffraction grating region is obtained by shifting the observation angle little by little. Above, "light" has a fixed "movement" at a predetermined speed, and using a pseudo-stereoscopic effect due to binocular parallax, the processing is more than the computer-generated hologram processing of the three-dimensional object itself The burden can be greatly reduced, the stereoscopic image itself becomes brighter and clearer in every corner, and its “movement” has high reproducibility at a defined speed and in a specified positional relationship within a three-dimensional space. Three-dimensional display image consisting of fine lines and its three-dimensional display that can be easily judged with high reliability by visual observation by selecting a simple light source or lighting environment in a general environment. Picture Providing is attached media.

Method of replacing an object surface by computer-generated hologram (CGH) with a set of point light sources One Example of Diffraction Grating Region having Shape Represented by Diffraction Grating of the Present Invention (“Shape” Group of Alphabet String “ABCDEF”) One Example of Stereoscopic Display Image of the Present Invention (Example of Developing Binocular Parallax. Only Alphabet A. The rest is omitted.) A method for producing a diffraction grating recording medium of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The diffraction grating used in the present invention causes a diffraction phenomenon with respect to a visible light source (for example, a light source having a wavelength of 380 nm to 750 nm), and the diffraction grating period is 0.6 μm to 1.6 μm. The diffraction grating has a concavo-convex structure of 0.1 μm to 0.4 μm, and has a diffraction efficiency of 20% or more when the diffraction grating region is uniformly formed within a 10 mm square.
The diffraction grating is created by the diffraction grating recording medium creation process shown in FIG.
In order to describe the embodiment of the present invention, in the following, an example of a diffraction grating region having a shape represented by the diffraction grating of FIG. 2 (a “shape” group of alphabetic character strings “ABCDEF”) is taken as an example. Use.
2A to 2F are individual diffraction grating regions, that is, “shapes” each represented by a predetermined diffraction grating, and are adjacent to each diffraction grating region as illustrated in FIG. 3. Thus, diffraction gratings having the same shape are provided. In FIG. 3, the letter “A” has a horizontal portion, so that it is adjacent to the lower right direction to make it easier to recognize binocular parallax.
The formation conditions of these character strings are as described above. An area surrounded by a solid line and an area surrounded by a broken line in FIG. 3 are multiple recording areas. Since this area has been subjected to multiple recording processing (not shown), the brightness is simply halved, so the same processing is performed for the non-overlapping areas (one area of the checkerboard pattern is blanked). Thus, the brightness of the diffraction grating can be made uniform.

When these character strings are observed under a predetermined illumination (a white light source is under only one fluorescent lamp, a single incandescent light bulb, or even a light source of a simple penlight), the diffraction grating is formed. Each character can be recognized at a position lifted by each distance, and when the observation angle is shifted little by little, a bright part (light region) having a specific color tone appears on A floating in the air, and is constant. While moving from B to F at a speed, it is possible to confirm the movement approaching again and approaching again reliably and with good reproducibility. Since this three-dimensional light movement is the same as the “light movement information” that is known in advance, it can be easily determined visually that this three-dimensional display image is authentic.
This means that if the change of the predetermined movement D in the upper part and the lower part of each character is the same (upper part 250 → 200 → 150, etc., lower part 350 → 300 → 250, etc., not shown), it floats in the air. It is possible to observe the movement of each character approaching or moving away from the diffraction grating forming surface while tilting in the perspective direction.
Further, when another set of A to F is provided in parallel at a distance of 20 mm from these forming positions, the movement of light is reversed and the lifting distance is also reversed, the “movement of light” for the above set. In addition, the “light movement” of the lower set can be made symmetrical, and can be observed simultaneously, and the accuracy of authenticity determination can be improved.
Of course, this arrangement of A to F may be arranged so as to draw a gentle curve, or two sets may be crossed. The portion where the diffraction gratings overlap at the intersecting portion is subjected to the multiple recording process described above.

For stereoscopic viewing by binocular parallax, the method of providing one adjacent “shape” and making it one pair has been described above. However, in order to create a more stereoscopic effect, two to four pairs may be used. In any case, it is desirable that the left and right sides are symmetrical. If there are two pairs, the predetermined distance D of the four “shapes” is, for example, 120 μm, 150 μm, 120 μm from the left, and if there are four pairs, 50 μm, 50 μm 55 μm, 60 μm, 55 μm, 50 μm, and 50 μm.
Similarly, one to four pairs can be formed on the left and right with one “shape” as the center. The “shape” in the center increases brightness and stability.
The diffraction grating specifications of this adjacent diffraction grating region are -15 degrees on the left side for one pair, +15 degrees on the right side, and -20 degrees on the left side and -10 degrees on the right side, and +10 degrees on the right side. , +20 degrees. Three pairs and four pairs can be set similarly.
When the original “shape” is placed at the center, for example, those having a diffraction grating angle of 0 degrees are set at these centers.
Also, when stereoscopic viewing is performed using the diffraction grating period, the difference between the left and right sides is 0.2 μm (1.0 μm and 1.2 μm) if there is one pair, and the left and right sides if there are two pairs. Is 0.1 μm and 0.2 μm (0.95 μm, 1.0 μm, 1.1 μm, and 1.15 μm). The same setting can be made when three pairs, four pairs, and the original “shape” are placed at the center.

Next, as shown in FIG. 4, data related to all diffraction gratings including adjacent diffraction gratings calculated by the spatial arrangement of “shape” set for these predetermined diffraction gratings is converted into an electron beam drawing data editing PC (personal computer). To the electron beam drawing data for operating the electron beam drawing apparatus, by inputting the edit data to the electron beam apparatus, on the electron beam drawing resist prepared in advance, using the electron beam drawing apparatus, Predetermined exposure (recording) is performed and development processing is performed to obtain a diffraction grating master.
In order to accurately copy the generated uneven shape, a precise original is directly reproduced using a curing type resin without using a metal thin film or the like to obtain a replica master faithfully reproducing the unevenness on the electron beam resist.

(Diffraction grating recording medium)
In order to produce a diffraction grating recording medium, first, a duplication sheet is used in which a transparent substrate is coated with a transparent resin capable of precisely duplicating the above-described irregularities.
As a transparent substrate, it is possible to reduce the thickness, and it has mechanical strength and solvent resistance and heat resistance that can withstand processing when manufacturing a diffraction grating recording medium sheet, label, and transfer sheet. Use things. Since it depends on the purpose of use, it is not limited, but a film-like or sheet-like plastic is preferable.
For example, various plastic films such as polyethylene terephthalate (PET), polycarbonate, polyvinyl alcohol, polysulfone, polyethylene, polypropylene, polystyrene, polyarylate, triacetyl cellulose (TAC), diacetyl cellulose, and polyethylene / vinyl alcohol can be exemplified. .
From the same consideration, the thickness of the transparent substrate is desirably 5 to 50 μm, particularly 5 to 15 μm. When forming the transfer sheet, a release layer made of a cellulose acetate resin or a methacrylic resin that is usually used may be provided on the transparent substrate.

(Diffraction grating forming layer)
Various resin materials such as various thermosetting resins, thermoplastic resins and ionizing radiation curable resins can be selected as the transparent resin material for constituting the diffraction grating forming layer. Examples of the thermosetting resin include unsaturated polyester resins, acrylic urethane resins, epoxy-modified acrylic resins, epoxy-modified unsaturated polyester resins, alkyd resins, and phenol resins. Examples of the thermoplastic resin include acrylate resin, acrylamide resin, nitrocellulose resin, and polystyrene resin. These resins can be used alone or as two or more types of copolymers. In addition, these resins may be used alone or in combination of two or more types of isocyanate resins, metal soaps such as cobalt naphthenate and zinc naphthenate, benzoyl peroxide, peroxides such as methyl ethyl ketone peroxide, benzophenone, acetophenone, anthraquinone, naphthoquinone, A heat or ultraviolet curing agent such as azobisisobutyronitrile or diphenyl sulfide may be blended. Examples of the ionizing radiation curable resin include epoxy acrylate, urethane acrylate, and acrylic-modified polyester. Other monofunctional or polyfunctional monomers, oligomers and the like can be conjugated to such ionizing radiation curable resins for the purpose of adjusting the cross-linking structure and viscosity.
The diffraction grating forming layer is formed by shaping by pressing the mold surface of the above-described replica master to the above resin material.
One side of a layer made of a transparent resin material that has been cured by curing by heating or irradiation with ionizing radiation while keeping an uncured thermosetting resin or ionizing radiation curable resin in close contact with the mold surface. It is possible to form fine irregularities of a precise diffraction grating.

The ionizing radiation curable resin is preferably (1) an isocyanate having at least three isocyanate groups in the molecule, and (2) at least one hydroxyl group and at least two (meth) acryloyloxy groups in the molecule. Using an ionizing radiation curable resin containing a polyfunctional (meth) acrylate, or (3) a urethane (meth) acrylate oligomer that is a reaction product of a polyhydric alcohol having at least two hydroxyl groups in the molecule, preferably A polyethylene wax may be included, applied, dried, and cured with ionizing radiation to form an ionizing radiation curable resin.
An ionizing radiation curable resin containing a urethane (meth) acrylate oligomer is disclosed in a cured product of an ionizing radiation curable resin containing a urethane (meth) acrylate oligomer, specifically, JP-A-2001-329031. The photocurable resin etc. which can be illustrated. Specific examples include MHX405 varnish (product name of ionizing radiation curable resin, manufactured by The Inktec Co., Ltd.)

(Formation of diffraction grating formation layer)
The formation of the diffraction grating forming layer is based on the above ionizing radiation curable resin, added with a photopolymerization initiator, plasticizer, stabilizer, surfactant, etc., and dispersed or dissolved in a solvent, on a transparent substrate. In addition, it may be applied by a coating method such as roll coating, gravure coating, comma coating, die coating, and the like, dried and reacted (cured) with ionizing radiation after shaping the fine irregularities. The thickness of the diffraction grating forming layer is usually about 1 to 10 μm, preferably 2 to 5 μm.
A reflective layer may be provided on the diffraction grating forming layer. A reflective thin film layer is formed so as to follow the uneven surface. Since this thin film layer needs to reflect incident light, it is not particularly limited as long as it is a thin film layer having a higher refractive index than the diffraction grating forming layer.
The reflective thin film layer may be a metallic glossy reflective layer that reflects visible light over almost the entire wavelength range, such as a metal thin film formed by vacuum deposition, sputtering, ion plating, etc., or light of a specific wavelength. Any of the transparent reflective layers that appear transparent depending on the viewing direction, etc. can be used because only the reflective direction is reflected. However, when a metallic glossy reflective layer is partially provided or a transparent reflective layer is provided, the transparent reflective layer is passed through. This is preferable because the design of the security object can be confirmed.
Examples of the metal material for forming the reflective thin film layer include Al, Cr, Ti, Fe, Co, Ni, Cu, Ag, Au, Ge, Mg, Sb, Pb, Cd, Bi, Sn, Se, In, A metal such as Ga or Rb, or an oxide or nitride of the metal can be used, and one or more of these can be used in combination. Among these, Al, Cr, Ni, Ag, Au, or the like is particularly preferable, and the film thickness is preferably 1 nm to 10,000 nm, more preferably 2 nm to 200 nm.
Moreover, in order to improve reflectivity, you may add a transparent reflective layer. The transparent reflection layer enhances the diffraction effect by being provided on the fine uneven surface and on the transparent reflection layer. The transparent reflective layer is a transparent reflective layer formed by a vacuum thin film method or the like.

As a transparent reflective layer, it has almost colorless and transparent hue, and its optical refractive index is different from that of the diffraction grating forming layer forming layer, so that it is possible to visually recognize glitter such as holograms even though there is no metallic luster. . For example, there are a thin film having a higher refractive index than that of the diffraction grating forming layer and a thin film having a lower refractive index. Examples of the former include ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂ S ₃ , SiO SnO ₂ , ITO, etc., and examples of the latter include LiF, MgF ₂ , and AlF ₃ . Preferably, it is a metal oxide or nitride, specifically, Be, Mg, Ca, Cr, Mn, Cu, Ag, Al, Sn, In, Te, Fe, Co, Zn, Ge, Pb, Cd , Bi, Se, Ga, Rb, Sb, Pb, Ni, Sr, Ba, La, Ce, Au, and other oxides or nitrides, and the like can be exemplified by a mixture of two or more thereof. The transparent metal compound is formed by vacuum thin film methods such as vapor deposition, sputtering, ion plating, and CVD so that the thickness of the diffraction grating forming surface is about 10 to 2000 nm, preferably 20 to 1000 nm, as in the case of the metal thin film. For example, it may be provided.

(Adhesive layer / adhesive layer)
As the adhesive layer, a known heat-sensitive adhesive that melts or softens when heated and exhibits an adhesive effect can be applied. Specifically, vinyl chloride resin, vinyl acetate resin, vinyl chloride vinyl acetate copolymer Examples thereof include resins, acrylic resins, polyester resins, and the like.
Examples of the adhesive resin include vinyl acetate resin, vinyl acetate butyrate resin, chloroprene rubber, isoprene rubber, and urethane resin.
Or, as an adhesive adhesive layer having both adhesiveness and thermal adhesiveness, an acrylic resin or rubber resin having adhesiveness and thermal adhesiveness, or a mixture of an adhesive resin and a thermal adhesive resin is applied. it can.
A layer having a thickness of 1 to 30 μm is prepared by dissolving or dispersing these resins in a solvent, adding an appropriate additive such as a pigment, and applying and drying by a known method such as roll coating, gravure coating, or comma coating. Get. When the surface of the security object is smooth like a film sheet, a thickness of 1 to 5 μm is preferable.
When the surface of the security object has a surface roughness of 30 μm or more like paper or cloth, the thickness of the adhesive layer / adhesive layer is 5 μm to 30 μm, and further 20 μm to 30 μm. Thickness is preferred.
In the case of a transfer sheet configuration having a release layer, the transfer sheet is stacked at a predetermined position on the surface of the security object, and after a predetermined heating and pressurization, the transparent substrate is peeled off to form a diffraction grating in a desired shape. By transferring the formation layer, the diffraction grating recording medium can be transferred.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, it is not limited to this. In addition, except a solvent, each composition of each layer is a mass part of solid content conversion.
Example 1
A diffraction grating region having a shape represented by a diffraction grating having a diffraction grating angle of 1 and a diffraction grating period of 1 is represented by alphabetic character strings “A” and “B” having a line width of 1 mm, a character height of 5 mm, and a character width of 4 mm. “C”, “D”, “E”, “F” (n = 6, a group of six “shapes”), and each “shape” is one adjacent adjacency having the same “shape” as the “shape”. Each of the diffraction grating regions has a predetermined movement (distance) D described below, and since the original “A to F” diffraction grating specifications and the horizontal direction regions of each character are large, the adjacent directions are inclined downward to the right ( 30 degrees downward), and the diffraction gratings were set according to the following specifications. The overlapping portion of the solid line area and the broken line area was divided into 50 μm square checkered areas as a multiple recording process, and the solid line area diffraction grating and the broken line area diffraction grating were alternately set. Furthermore, the non-overlapping portions were divided into similar checkered areas, and a predetermined diffraction grating was set to skip one.
The individual specifications are as follows.
Diffraction grating period dn, diffraction grating angle θn, predetermined movement D, period change d0, angle change θ0,
Angle change α of adjacent diffraction grating region, d0 = 0.1 μm, θ0 = 6 degrees.
A: d1 = 0.7 μm, θ1 = −24 degrees, D = 80 μm
Adjacent region of A (α = 15 degrees): period = 0.7 μm, angle = θ1 + α = −9 degrees B: d2 = 0.8 μm, θ2 = −18 degrees, D = 120 μm
Adjacent region of B (α = 15 degrees): period = 0.8 μm, angle = θ2 + α = −3 degrees C: d3 = 0.9 μm, θ3 = −12 degrees, D = 160 μm
Adjacent region of C (α = 15 degrees): period = 0.9 μm, angle = θ3 + α = 3 degrees D: d4 = 1.0 μm, θ4 = −6 degrees, D = 160 μm
Adjacent region of D (α = 15 degrees): period = 1.0 μm, angle = θ4 + α = 9 degrees E: d5 = 1.1 μm, θ5 = 0 degree, D = 120 μm
E adjacent region (α = 15 degrees): period = 1.1 μm, angle = θ5 + α = 15 degrees F: d6 = 1.2 μm, θ6 = 6 degrees, D = 80 μm
An adjacent region of F (α = 15 degrees): period = 1.2 μm, angle = θ6 + α = 21 degrees, and the distance between the six “shapes” was set to 2 mm and arranged in the horizontal direction to set a stereoscopic display image.

By inputting data related to these diffraction gratings to an electron beam drawing data editing PC (personal computer), editing the electron beam drawing data for operating the electron beam drawing apparatus, and inputting the editing data to the electron beam device, Predetermined exposure (recording) was performed on an electron beam lithography resist prepared in advance using an electron beam lithography apparatus, and development processing was performed to obtain a diffraction grating master.
Next, an electron beam curable resin composition having high physical properties is applied to one side of a transparent substrate (polyethylene terephthalate film) having a thickness of 50 μm, and an electron beam is irradiated while the mold surface of the diffraction grating master is kept in contact. The electron beam curable resin composition was cured to form a diffraction grating forming layer having a thickness of 5 μm and fine irregularities of the diffraction grating. On this fine unevenness, a reflective aluminum thin film of 100 nm is provided by a vacuum deposition method, and the following composition is coated on the reflective aluminum thin film forming surface so that the coating amount after drying with a gravure coater is 20 μm. After drying at 70 ° C. to form an adhesive layer, the diffraction grating recording medium of Example 1 was obtained as a circular seal with a diameter of 25 mm.
・ <Adhesive composition>
Vinyl acetate-acrylic copolymer 30 parts by mass Toluene 40 parts by mass Vinyl acetate 40 parts by mass When this is pasted on a gift certificate and observed under a plurality of fluorescent lamps via a diffusion plate, six letters are rainbow-colored However, when observed with a simple penlight, the bright lines on the six letters move at a constant speed from A to F according to the tilting movement of the diffraction grating recording medium. We were able to clearly confirm the "movement" that moved away from the forming surface at a high speed and returned to the original.
It was possible to determine that the gift certificate was genuine by this “movement” method.

(Example 2)
Example 2 was obtained in the same manner as Example 1 except that the angle change α of the adjacent diffraction grating region was changed to the period change β of the adjacent diffraction grating = 0.2 μm.
The observation result was the same as in Example 1.
(Example 3)
The predetermined movement D is
+ 20μm at the top of letter A, -20μm at the bottom
+40 μm at the top of letter B, −40 μm at the bottom
-40 μm at the top of letter C, +40 μm at the bottom
+20 μm at the top of the letter D, −20 μm at the bottom
-60 μm at the top of the letter E, -60 μm at the bottom
+20 μm at the top of the letter F, -20 μm at the bottom
Example 3 was obtained in the same manner as in Example 1 except that.
The observation results show that each character illuminates toward the back side or illuminates toward the front, moves away from the forming surface, returns to the original, and the light moves at a constant speed from left to right. "Could be confirmed clearly.
It was possible to determine that the gift certificate was genuine by this “movement” method.
Example 4
In each adjacent diffraction grating area, another adjacent diffraction grating area having a predetermined movement D in the opposite direction is set, and the angle change α of the adjacent diffraction grating area is set as (−15 degrees). Example 4 was obtained in the same manner as Example 1.
Although the observation result was the same as that of Example 1, the brightness of light was stronger and the viewing angle capable of stereoscopic viewing could be confirmed wider.

(Comparative Example 1)
Comparative Example 1 was obtained in the same manner as Example 1 except that the adjacent diffraction gratings were not provided for the letters A to F.
When observed in the same manner as in Example 1, the bright line moved from A to F at a constant speed in accordance with the movement of tilting the diffraction grating recording medium, but there was no three-dimensional movement, and the gift certificate was authentic. It was not possible to determine that it was.
(Comparative Example 2)
A predetermined movement D of adjacent diffraction gratings of letters A to F is
Movement D: 100, 200, 400, 600, 800, 1000 μm
Comparative Example 2 was obtained in the same manner as Example 1 except that
When observed in the same manner as in Example 1, the bright line of light moved at a constant speed from A to F according to the tilting movement of the diffraction grating recording medium, but moved three-dimensionally from A, B, and C. Although the situation was confirmed, D, E, and F were not observed as three-dimensional movements, but were observed only as characters swelled and shining, and it was not possible to determine that the gift certificate was authentic.
(Comparative Example 3)
Except for setting the angle change α of the adjacent diffraction grating region as A = 5 degrees, B = 25 degrees, C = 40 degrees, D = 50 degrees, E = 60 degrees, and F = 75 degrees, all are the same as in the first embodiment. Thus, Comparative Example 3 was obtained.
When observed in the same manner as in Example 1, the bright line of light moved from A to F at a constant speed according to the tilting movement of the diffraction grating recording medium, but moved in three dimensions from A, B, and C. However, in D, E, and F, it was observed that the letters were only swelled and shining rather than three-dimensional movements, and the gift certificate could not be determined to be authentic.

(Evaluation results)
In Examples 1 to 4, it was possible to reliably determine the movement of the light moving three-dimensionally. In particular, Example 4 was able to confirm brighter movement of light and also to confirm the spread of the viewing angle.
In addition, as an observation light source, it was possible to make a determination using a single fluorescent lamp, a single incandescent lamp, and a handy type LED light source.
In Comparative Example 1, there was no three-dimensional movement. In Comparative Examples 2 and 3, although some stereoscopic effects were confirmed, some stereoscopic images could not be viewed stereoscopically, which seemed insufficient for authenticity confirmation.

ST1 to ST7: Steps for creating a computer-generated hologram (CGH) A, B, C, D, E, F: Diffraction grating region of each shape 1 Solid line region (diffraction grating region)
2 Dashed area (adjacent diffraction grating area)
3 Overlapping area (Multiple recording area)
ST10 to ST18: Steps for creating a diffraction grating recording medium

Claims (3)

Made plural pieces shaped diffraction grating region having a shape represented by a diffraction grating having a diffraction grating angle and the grating period is arranged in a predetermined direction, and, adjacent each of the diffraction grating region, the diffraction grating becomes the area and set, Oite to the diffraction grating region and adjacent diffraction grating region having the same shape consisting of n sets of diffraction grating areas are provided at least one stereoscopic display picture images,
Each diffraction grating region and the adjacent diffraction grating region to be paired are arranged so that a part of the region overlaps with the region,
The diffraction grating angle θn and the diffraction grating period dn of each diffraction grating region change in the predetermined direction at a predetermined ratio of the diffraction grating angle θ0 and the diffraction grating period d0, and
The grating angle of the grating adjacent diffraction grating region to be the diffraction grating region and the set is, the stereoscopic display image, wherein the benzalkonium different only α than the diffraction grating angle θn of the diffraction grating region. Made plural pieces shaped diffraction grating region having a shape represented by a diffraction grating having a diffraction grating angle and the grating period is arranged in a predetermined direction, and, adjacent each of the diffraction grating region, the diffraction grating becomes the area and set, Oite to the diffraction grating region and adjacent diffraction grating region having the same shape consisting of n sets of diffraction grating areas are provided at least one stereoscopic display picture images,
Each diffraction grating region and the adjacent diffraction grating region to be paired are arranged so that a part of the region overlaps with the region,
The diffraction grating angle θn and the diffraction grating period dn of each diffraction grating region change in the predetermined direction at a predetermined ratio of the diffraction grating angle θ0 and the diffraction grating period d0, and
The diffraction grating period of the diffraction grating of the adjacent diffraction grating region to be the diffraction grating region and the set is, the stereoscopic display image, wherein the benzalkonium different only β than the diffraction grating period dn of the diffraction grating region. Diffraction grating recording medium a stereoscopic display image is formed according to claim 1 or 2.

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